Question

In the collecting ducts of the juxtamedullary nephrons Select one:

a. Water and sodium reabsorption always occur together

b. Substances are always actively transported in the same direction as sodium

c. Aquaporins are produced when angiotensin 2 is present

d. None of the above are correct

Answer 1

There are two types of nephron

1. Cortical

2. Juxtamedullary

both the nephron are responsible in concentration of urine. as we studied in RAAS system that when sodium is reabsorbed in body of dehydrated person water reabsorption also takes place simultaneously so that body's homeostasis is maintained.

Answer: Water and sodium reabsorption always occur together

All substances are not actively transported with sodium in same direction, take an example of Na+/K+ pump when there is active transport Na+ comes out of the cell and k+ goes inside the cell.

Aquaporins are already present in kidneys they are not produced by Angiotensin 2, but Angiotensin 2 stimulate the release of ADH by the posterior pituitary. ADH acts to increase water reabsorption in the kidney by inserting aquaporin channels at the collecting duct.